Study aims to tailor PKU drug dosing for patients with organ impairment

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion criteria: 1. Body mass index (BMI) from 18.0 to 38.0 kilograms per square meter (kg/m\^2) (inclusive). 2. Able to provide written, informed consent. 3. Male participants and female participants of childbearing potential (POCBP) must agree to remain fully abstinent from intercourse where pregnancy can occur OR practice 2 different contraceptive methods, where at least one must be highly effective. 4. Otherwise be in generally good health. 5. Additional criteria for Group 1: i. Have moderate hepatic impairment determined using Child-Pugh classification (Class B). ii. Have relatively stable hepatic function for the duration of the study as determined by the investigator and liver function test at the time of screening or stable hepatic function 1 year prior to screening. iii. Have normal renal function. iv. Have a clinical diagnosis of hepatic cirrhosis based on biopsy and/or clinical criteria. 6. Additional criteria for Group 2: i. Have estimated glomerular filtration rate based on the Chronic Kidney Disease-Epidemiology Collaboration (eGFRCKD-EPI) lesser than (\<) 30 milliliters per minute per 1.73 square meters (mL/min/1.73 m\^2) indicating severe renal impairment. ii. Not currently be on dialysis. iii. Have relatively stable renal function as determined by eGFRCKD-EPI. 7) Additional criteria for Group 3: i. eGFRCKD-EPI greater than or equal to (≥) 90 mL/min/1.73 m\^2 indicating normal renal function. ii. Have liver enzymes within normal limits. Exclusion criteria: 1. Participants who are breastfeeding. 2. Participants who have a positive pregnancy test result prior to receiving the investigational medical product (IMP). 3. Participants with international normalized ratio (INR) greater than (\>) 2.3. Participants with hepatic impairment with elevated INR will be excluded based on the investigator's discretion. 4. Participants with hepatic carcinoma or porto-hepatic shunts that have been surgically created or planted. 5. A history of difficulty in obtaining intravenous access. 6. The donation of blood or plasma \> 250 milliliters (mL) within 30 days prior to screening or received \> 50 mL of blood or plasma within 30 days prior to screening. 7. Participants who have taken an investigational drug within 30 days prior to screening. 8. Exposure to any substances known to stimulate hepatic microsomal enzymes within 30 days prior to screening (eg, occupational exposure to pesticides, organic solvents, etc). 9. Any participant who, in the opinion of the investigator, should not participate in the trial. 10. Previous exposure to repinatrabit. 11. Additional criteria for Group 1: History of serious mental disorder including participants who have greater than Grade 1 encephalopathy as assessed by the Child-Pugh score and/or the investigator's judgment. 12. Additional criteria for Group 2: i) Participants that have undergone a renal transplant. ii) Participants expected to require dialysis within 45 days. iii) Clinically significant abnormal findings in the serum chemistry, hematology, or urinalysis results obtained at screening or on Day -1, other than those associated with underlying renal conditions and other stable medical conditions consistent with the disease processes. 13. Additional criteria for Group 3: History of or current hepatitis, or carriers of hepatitis B surface antigen (HBsAg) and/or hepatitis C antibodies (anti-HC). Note: Other protocol-specified inclusion/exclusion criteria may apply.